Shielded cable construction providing for an internal connection to ground

ABSTRACT

A shielded cable construction provides for an annular clearance space between the inner and outer insulation jackets so that a grounding member can be inserted therein and internally connected with the cable shield without need for stripping insulation or taping.

United States Patent CRIN/PING 2 c 01.1.1

Brazee Feb. 15, 1972 [54] SHIELDED CABLE CONSTRUCTION 3,233,036 2/ 1966, Jachimowicz "174/107 3,360,409 12/ 1967 Jachimowicz et al.. .174 105 X PROVIDING FOR AN INTERNAL 3,340,353 9/1967 Mildner ..l74/l06 CoNNECTION To GROUND 3,130,256 4/1964 Mildner 174/102 x 72 Inventor: John A. Bram waningford, Conn. 3,272,91 l 9/1966 Rolirns et a1. 1 74/106 [73] Assignee: The Whitney Blake Company, New Haven,

Conn.

[22] Filed: 1970 Primary Exanu'ner--Lewis H. Myers [21] AppL 78,529 Assistant Examiner-A. T. Grimley Attorney-Blair, St. Onge and Mayers [52] U.S. Cl. 174/107, l74/78, 339/276 R AB TRACT [51] Int. Cl ..H02g 15/02, 01b 1 H06 A shielded cable construction provides for an annular Field of Search 75 75 7 clearance space between the inner and outer insulation 174/ 105, 106, 107, 36; 339/95 R, 96, 97 R, 97 C, jackets so that a grounding member can be inserted therein 100 223 R 276 R, 276 T and internally connected with the cable shield without need for stripping insulation or taping. [56] References Cited UNITED STATES PATENTS 2,930,835 3/1960 Bollmeier 174/76 l0 Claims, 3 Drawing Figures Shielded cable ismuchuised the communications industry, particularlyin the'construction'of telephone lines. Two

common applications for shielded telephone cable are as'ser vice cable which isused to connect achsubscriber toadistribution point, andas distribution cable which is'used in branching off from a feeder cable to serve a small area or a building. Shielded cable is normally terminated with the.

metallic shield being connected to ground. There have, however, been problems in making such ground connectionswith Prior art shielded cables. 1

The ground connection to a prior art shielded cableis typically made by stripping back the outer cable jacketand crimping or soldering aground connector directly to the shield. ln-

sulating tape is then applied over the connection to replace the outer jacket insulation. However, sincethe outer jacket is sometimes bonded ,to the shield, strippingis difficult to perform. Breakage often occurs in the shield as the outer jacket is pulled off, and this necessitatesfurther stripping untila successful connection can be made. v

Moreover, the bulky, taped construction of prior art ground connections have prevented them from being inserted into certain types of housings used by the telephone industry. This type of taped groundf connection has therefore frequently been left exposed where it isunsightlyand subject to tamper ingor other physical damage.

ing,-in which? throughout theseveral views of the-drawi BRIEF DESCRIPTIONOFTHE DRAWING j I For-a fuller understanding of the nature and objects of'the invention, reference should be had to the following detailed description taken in connection with the accompanying draw- FlG. l isa perspective view of the shielded cable of the invention showing a grounding lug internally "connected to'the shieldthereof. w FIG. 2 is an enlarged sectional view of the cable taken along line22ofFlG.'l. "V f i 3 FIG. 3 is an enlarged sectional view of the cable taken along line Iii-13 of FlG.-'1 and showing the internal connection between the grounding lugand the cable shield.

-Similar reference characters refer'gito similar parts bescaii riouos HEinterlinkedEmmott/Isms-" ea -n; new is nos. 1 aha 2,11,; shielded as; to the invention comprises an innercore l2 shownhere as co'm'prismg four separate insulated Candace; wires-12a, 12b,12 C and l 2d. .'Alternatively, core l2 mayjcomprise a'fs'i ngle insulated conductor of a greater number'of separate insulated conductors in accordance with the ultimate application for the cable. Col-e112 is surrounded by a preferably extruded inner insulating jacket 14. Alternatively, jacket 14 may be an insulating tape covering. Jacket 14 may be formed of any suitable elec- Accordingly, representative objects of the present invention I are to provide a shielded cable construction which provides for. an internal ground connection to the shield, said cable construction eliminating the need for. stripping the outer jacket and taping, and providing for easily made strong, reliable and aesthetic ground connection.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

' I The invention accordingly comprises'the features of construction, combinations ofelements, and arrangementof parts which will be exemplified inthe constructions hereinafter set forth, and the scope of the invention'will be indicated inthe claims.

suMMARv'oFfTiiEim/ zNTioN trical insulation m'aterial'such as polyethylene, polypropylene,

polyvinylchloride or combinations ofthese and/or other.

similar insulating materials. I a lnner jacket 14 is'in turn surrounded by an outer insulating jacket-16 also formed from a. suitable electricaljinsulating material. Outer jacket '16, however, has a significantly larger inner diameter than the outer diameter of inner jacket 14.

1 Thus, a clearly defined clearance space 18 is left between the two jackets and extends the length of the cable. A p

' As is more fully described hereinafter, clearance space vl8 permits the internal connection of a grounding member to the cable shield. The size of the clearance space may vary depend; ing upon'overall cable diameter andthesi'ze of the grounding 1 member to be used. it will also be understood that thesize of the clearance space will vary 'frompoint to point along an actual cable dueto displacement of the inner jacket with respect to the outer jacket. However, the, clearance spaceiis clearly defined in an actual'cable 'and'hasasubstantially uniform The present invention relates to a shielded cable construction which providesfor an internal connection of the shield to ground. For this purpos'ethe cable isconstructed with an annularclearance -space between the shield and inner jacket. The clearance space is a result of differing inner and outer insulating jacket diameters. The metallic cable shield is made contiguous with the inner surface of the outer jacket, and is preferably bonded thereto to reinforce the shield against breakage. As a result of the cable construction, a grounding lug or similar groundingmember can' be inserted into the clearance space through a free end or terminus of the cable. The grounding member is thereby brought into internal electrical contact with the shield. The electrical contact can be enhanced and the connection made substantially permanent by preferably crimping the surrounding cable.

Thus, the shielded cable construction of the invention eliminates the need for stripping the outer jacket in order to make a ground connection. There is also no need for applying bulky insulating tape to the connection. Accordingly, no difficulty is encountered in enclosing ground connections made to the cable of the invention, and the connections are far less A unsightly and more durable and tamperproof than prior art average widthw (FIG. 2); an'exa'mple, ina shielded'cable constructed for use as a' two-pair buried telephone service "wire, a clearance space of 0,022 inch has been provided to accommodate a grounding lug 19 of the type shown in FIG. I. Still'referrin'gto FIGS. 1 andZ, the cable shield 20 "comprises a thin metallic 'ribbon' which'surroundsinner jacket 14 with its side edges lapped over as at 21 to form a longitudinal seam. Shield 20 is spaced from the inner jacket to preserve clearance space 18 and is' contiguous with the inner surface of outer jacket 16. Shield 20 is also preferably bonded to jacket 16 so that the jacket serves to reinforce the shield against breakage when the cable is flexed or stressed. I

Cable shield 20 may be formed of any electrically conductive metal, copper and aluminum being typical'for commercial cable. However, when the cable is to be buried in use, a stronger material is required to resist the gnawing of rodents. For this purpose shield 20 may be formed of a laminate of stainless steel and aluminum, or stainless steel and copper. in

I both cases the stainless steel provides strength for rodent resistance and the aluminum'or copper provides the requisite electrical conductivity. Such a laminated shield is oriented in the cable with the conductive metal innermost so that connecly, the shield may be uniformly made from bronze, a material incorporating both strength and sufficient conductivity.

in cables where shield 20 is bonded to outer jacket 16, a coating may be applied to the shield to facilitate bonding; for example, in the case of an aluminum shield bonded to a tion can be readily made to a grounding member. Alternative- I polyethylene outer jacket, the shield has been coated with a thin polyolefin film. The thus coated aluminum is known as fused polyolefin coated aluminum" and the polyolefm coating aids in corrosion resistance as well as producing a strong bond with the outer polyethylene jacket.

The grounding member used with the cable of the invention may take a variety of forms and sizes; for example, a single electrical conductor wire may be inserted into clearance space 18 and crimped, soldered or otherwise secured in position in electrical contact with shield 20. The protruding end of the wire may then be connected to ground.

Preferably, however, the grounding member takes the form of a lug 19 as shown in FIG. 1. Lug 19 has a terminal portion 22 at one endwhich may be a spade type as shown, or circular or any other functional terminal shape. The other end of lug 19 comprises an elongated prong 24 which is preferably tapered and of arcuate cross section so as to be readily insertable into clearance space 18 as shown in FIG. 3.

it can be seen from FIG. 3 that once inserted into clearance space 18, prong 24 of lug 19 is urged into internal electrical contact with shield 20 as a result of pressure from the eccentrically displaced inner jacket 14 and enclosed core 12. For a more positive and stronger electrical connection, however, lug

19 is preferably crimped in place within the cable. Referring to FIGS. 1 and 3, crimping is preferably performed with the aid of a metal crimping collar 26. Collar 26 is preferably split as shown at 28 and is coaxially mounted on the end of the cable about lug 19. The collar is then compressed with a pair of pliers or other suitable tool into tight engagement with outer jacket 16, thereby compressing the structure of the cable and causing a secure and positive engagement between prong 24 of lug l9 and shield 20 as shown in FIG. 3.

The provision of a clearance space in the cable of the invention also facilitates the stripping of portions of the outer jacket and shield when desirable. One need merely ring the outer jacket and shield as with a knife by cutting through the outer jacket and scoring the shield. A few reverse bends will then snap the shield at the point where it is scored. The severed portion may then be readily removed by sliding it from the remaining cable structure. It can be seen that the provision of a clearance space facilitates both reverse bending during severing and the subsequent removal of the severed portion.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A shielded cable construction with an internal connection to ground comprising, in combination:

A. an inner insulating jacket surrounding at least one conductor wire,

B. an outer jacket surrounding said inner jacket and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable,

C. a metallic shield in substantially contiguous contact with the inner surface of said outer jacket and spaced from said inner jacket, and

D. a grounding member extending at one end from the cable terminus and with the other end thereof disposed in said clearance space between said inner jacket and said metallic shield and making electrical contact with said metallic shi l 2. A s hiblded cable construction having means for internally connecting the shield to ground comprising, in combination:

A. a cable comprising,

I. an inner insulating jacket surrounding at least one conductor wire,

2. an outer jacket surrounding said inner jacket and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable, and

3. a metallic shield in substantially contiguous contact with the inner surface of said outer jacket and spaced from said inner jacket,

B. a grounding lug having a terminal portion at one end extending from the cable terminus and a prong at the other end,

1. said prong being of arcuate cross section and being disposed in said clearance space between said inner jacket and said metallic shield and making electrical contact with said metallic shield.

3. A shielded cable construction as defined in claim 2 wherein the terminus of said cable surrounding said grounding lug is crimped to secure said lug in place and insure electrical contact between said lug and said shield.

4. A shielded cable for use with an internally connected grounding lug comprising, in combination:

A. an inner insulating jacket surrounding at least one conductor wire,

B. an outer jacket surrounding said inner jacket and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable for accommodating said grounding lug, and

C. a metallic shield in substantially contiguous contact with the inner surface of said outer jacket and spaced from said inner jacket.

5. A shielded cable as defined in claim 4 wherein said shield is formed of fused polyolefin coated aluminum, said outer jacket being directly bonded to said shield.

6. A shielded cable as defined in claim 5 wherein said outer jacket is formed of polyethylene.

7. A shielded cable as defined in claim 4 wherein said shield is formed of a laminate of stainless steel and aluminum.

8. A shielded cable as defined in claim 4 wherein said shield is formed of bronze.

9. A shielded cable as defined in claim 4 wherein said shield is formed of a laminate of stainless steel and copper.

10. A shielded cable construction with an internal connection to ground comprising, in combination:

A. an inner insulating jacket surrounding at least one conductor wire,

B. a metallic shield surrounding said inner jacket,

C. an outer jacket surrounding said inner jacket and shield and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable, and

D. a grounding member extending at one end from the cable terminus and with the other end thereof disposed in said clearance space and making electrical contact with said metallic shield. 

1. A shielded cable construction with an internal connection to ground comprising, in combination: A. an inner insulating jacket surrounding at least one conductor wire, B. an outer jacket surrounding said inner jacket and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable, C. a metallic shield in substantially contiguous contact with the inner surface of said outer jacket and spaced from said inner jacket, and D. a grounding member extending at one end from the cable terminus and with the other end thereof disposed in said clearance space between said inner jacket and said metallic shield and making electrical contact with said metallic shield.
 2. A shielded cable construction having means for internally connecting the shield to ground comprising, in combination: A. a cable comprising,
 2. an outer jacket surrounding said inner jacket and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable, and
 3. a metallic shield in substantially contiguous contact with the inner surface of said outer jacket and spaced from said inner jacket, B. a grounding lug having a terminal portion at one end extending from the cable terminus and a prong at the other end,
 3. A shielded cable construction as defined in claim 2 wherein the terminus of said cable surrounding said grounding lug is crimped to secure said lug in place and insure electrical contact between said lug and said shield.
 4. A shielded cable for use with an internally connected grounding lug comprising, in combination: A. an inner insulating jacket surrounding at least one conductor wire, B. an outer jacket surrounding said inner jacket and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable for accommodating said grounding lug, and C. a metallic shield in substantially contiguous contact with the inner surface of said outer jacket and spaced from said inner jacket.
 5. A shielded cable as defined in claim 4 wherein said shield is formed of fused polyolefin coated aluminum, said outer jacket being directly bonded to said shield.
 6. A shielded cable as defined in claim 5 wherein said outer jacket is formed of polyethylene.
 7. A shielded cable as defined in claim 4 wherein said shield is formed of a laminate of stainless steel and aluminum.
 8. A shielded cable as defined in claim 4 wherein said shield is formed of bronze.
 9. A shielded cable as defined in claim 4 wherein said shield is formed of a laminate of stainless steel and copper.
 10. A shielded cable construction with an internal connection to ground comprising, in combination: A. an inner insulating jacket surrounding at least one conductor wire, B. a metallic shield surrounding said inner jacket, C. an outer jacket surrounding said inner jacket and shield and being of a larger inner diameter than the outer diameter of said inner jacket to produce a substantially annular clearance space therebetween extending the length of said cable, and D. a grounding member extending at one end from the cable terminus and with the other end thereof disposed in said clearance space and making electrical contact with saId metallic shield. 